The present invention relates to an eyepiece attachment structure for an observing optical instrument.
The prior art includes an observing optical instrument such as a telescope employing a collet type attachment structure for removably attaching an eyepiece to a body of the observing optical instrument. The collet type attachment structure is configured such that the eyepiece includes an attaching sleeve generally cylindrically formed, and the body of the observing optical instrument is provided with a holding ring that receives and presses an outer circumferential surface of the attaching sleeve so that the eyepiece is frictionally engaged and fixed to the body.
However, if the eyepiece is a zooming type one, magnification of which is changeable by rotating a zooming ring provided thereto, when the zooming ring is rotated in a circumferential direction, the rotation torque prevails against the frictional engagement of the attaching sleeve with the holding ring, and the attaching sleeve is rotated with respect to the body.
It is therefore an object of the invention to provide an improved eyepiece attachment structure for an observing optical instrument, with which an eyepiece can be securely attached to the observing optical instrument and which allows easy detachment.
For the above object, according to the invention, there is provided an eyepiece attachment structure for attaching an eyepiece to an observation optical instrument, which is provided with a cylindrical attaching sleeve protruding from the eyepiece, a holding member secured to the body, the holding member frictionally holding the attaching sleeve when the attaching sleeve is inserted into the observation optical instrument, and a rotation preventing mechanism that mechanically prevents rotation of the attaching sleeve relative to the holding device when the attaching sleeve is inserted into the observation optical instrument.
With the above configuration, the eyepiece does not rotate while the eyepiece is movable in the axial direction.
Optionally, the holding member includes an elastically constrictable holding ring in which said attaching sleeve is inserted, an operating ring that is engageable with said holding ring, said holding ring being constricted upon operation of said operating ring, and a protecting element provided inside said holding ring, said protecting element frictionally engaging with said attaching sleeve when said holding ring is constricted.
Optionally, the rotation preventing mechanism may be provided with at least one rotation preventing groove provided on one of the eyepiece and the body, and at least one rotation preventing pin engageable with the at least one rotation preventing groove, the at least one rotation preventing pin being provided on the other one of the eyepiece and the body.
In this case, the at least one rotation preventing pin may be provided on the body, the at least one rotation preventing pin projecting inward in a radial direction of the holding member. Further, the at least one rotation preventing groove is formed at a front end portion of the attaching sleeve by cutting at least one portion of its outer circumferential surface.
Further optionally, another eyepiece having another attaching sleeve may be attachable with the attachment structure, the length of the another attaching sleeve along its axis being shorter than that of the attaching sleeve, and the another attaching sleeve does not interfere with the rotation preventing pin in an axial direction.
Alternatively, the rotation preventing pin may be movable between a locked position, at which the at least one rotation preventing pin engages the at least one rotation preventing groove, and an unlocked position, at which the at least one rotation preventing pin does not engage the at least one rotation preventing groove, and the eyepiece attachment structure may include a biasing means that biases the rotation preventing pin to be neutrally located at the locked position.
In this case, the rotation preventing pin may be movable in the radial direction of said holding member to locate between said locked position and said unlocked position, with being biased to neutrally locate at the locked position. Another eyepiece having another attaching sleeve is attachable with the attachment structure. The another attaching sleeve may be provided with a pin-lifting surface, which lifts the rotation preventing pin being to locate at the unlocked position upon insertion thereof into the holding member. With this configuration, an attaching sleeve which is not formed with the rotation preventing groove can be inserted in the observation optical instrument for use, without interfered by the rotation preventing pin.
Still optionally, the at least one rotation preventing groove may include a plurality of slits formed on the holding ring which enable the holding ring to be elastically constricted, and the rotation preventing pin may be provided on one of the attaching sleeve and a member integrally formed with the attaching sleeve.
In the above case, the at least one rotation preventing pin may be movable between a locked position, at which the at least one rotation preventing pin engages the at least one rotation preventing groove, and an unlocked position, at which the at least one rotation preventing pin does not engage the at least one rotation preventing groove, and the eyepiece attachment structure may include a biasing means that biases the rotation preventing pin to be neutrally located at the locked position.
Further, the rotation preventing pin may be movable in a direction parallel to an insertion/withdrawal direction of the attaching sleeve with respect to the body.
Still optionally, the eyepiece may be provided with a fixed cylinder integrally formed with the attaching sleeve, and a rotatable ring manually operable from outside. The rotatable ring may preferably be rotatably supported by the fixed cylinder.
In this case, the rotatable ring may be a zooming operation ring, upon operation of which, magnification-varying lens groups, supported in the eyepiece, may move along an optical axis to vary the focal length of the eyepiece.